Unlike front, center, and surround audio speakers, subwoofers are non-directional (audio pro, Jeff Berryman, does a good job of explaining why). That means you can place and position subs in almost any part of a room, which is great because subs can be large and unsightly. But Fredrik of Malmö, Sweden didn't want his sub anywhere in sight...
"I was disappointed of the Sony sub I had and also wanted a very clean installation in my living-room. So an idea grew in my mind and after some calculation I found a great JBL speaker that was able to handle both small boxes and high power, so together with my 400W Zachry that not was used for another project they fitted very well in to the volume of a [IKEA] Bestå shelf."
It's undoubtedly a beautiful IKEA hack, though we note this probably won't endear you with any neighbors underneath or close by! Here are a couple of other examples of IKEA pieces altered to house subs.
(Images: Fredrik/IKEA Hackers)